Conventional cellular and new personal communications systems (PCS) are currently enjoying increasing demand throughout the United States and the world. A majority of urban and suburban areas have at least one communication system currently in use or planned to be installed. The large size of conventional cellular antennas make it difficult to find suitable sites for placement, especially in metropolitan areas.
The large size of a cellular antenna is due in part to several requirements for a mobile communication system. First, the antenna generally must be capable of simultaneously transmitting and receiving radio frequency signals. Secondly, both the receiving and transmitting antennas must be, in most cases, omnidirectional, meaning that the antenna is capable of receiving and transmitting in all horizontal directions. Finally, the antennas must have a high gain or large power density in a preferred direction of radiation.
Presently, cellular antennas consist of arrays of patch antennas that transmit and receive electromagnetic radiation. Patch antennas are particularly suitable for use in mobile communication systems because of their size. The size of a cellular antenna is further reduced by physically locating the patch antennas close to one another. However, patch antennas interact with one another resulting in mutual coupling that adversely effects the performance of the communication system.
Accordingly, there is a need for a mutual coupling neutralizer to substantially neutralize mutual coupling between patch antennas. There is also a requirement to provide smaller cellular antennas without sacrificing performance. These and other needs are satisfied by the mutual coupling neutralizer of the present invention.